The present invention relates to a power supply voltage stabilizer and, more particularly, to a power supply voltage stabilizer employing a switching system for controlling power supply to a transformer included in the power supply voltage stabilizer.
In the conventional power supply voltage stabilizer employing a switching system for controlling power supply to a transformer included in the power supply voltage stabilizer, there is a possibility that an abnormal overvoltage will be developed from an output terminal thereof and/or an abnormal overcurrent may flow through the primary winding of the transformer.
Accordingly, an object of the present invention is to provide a protection means for protecting the power supply voltage stabilizer from an abnormal overvoltage and/or overcurrent.
Another object of the present invention is to provide a detection means for detecting an impending overvoltage and/or overcurrent occurring within the power supply voltage stabilizer.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
The power supply voltage stabilizer of the present invention mainly comprises a transformer including a primary winding connected to a commercial power source through a rectifying circuit, a secondary winding for output purposes, and an auxiliary winding. A driver circuit including a switching means is connected to the primary winding for controlling the power supply to the primary winding. An oscillator circuit is associated with the switching means to control ON/OFF operation of the switching means, thereby controlling the power supply to the primary winding.
To achieve the above objects, pursuant to an embodiment of the present invention, an overvoltage detection circuit is connected to the auxiliary winding. The overvoltage detection circuit functions to compare a voltage created in the auxiliary winding with the rectified power supply voltage, and develop a control signal, when an impending overvoltage is detected, for terminating operation of the oscillator circuit, thereby precluding power supply to the primary winding.
In another embodiment of the present invention, an overcurrent detection circuit is provided for detecting an impending overcurrent flowing through the primary winding to develop a control signal for terminating operation of the oscillator circuit.